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Regular Planning Commission Meeting Minutes – Wednesday, September 2, 2015 Page 10 Questions of Staff in response to Public Comment 454 Member Cunningham noted two significant concerns for her: tree preservation, and her 455 desire that a revised tree preservation ordinance was available even though she 456 understood it was in process and not yet ready for adoption, which she found unfortunate 457 given the number of large trees being proposed for removal from this project area. Also of 458 concern, Member Cunningham advised was the water drainage and runoff as referenced 459 by Mr. Ramalingam in his written comments, and expressed her curiosity in whether 460 there was actually a potential for “gallons of water” to address as a result of additional 461 house foundations and impervious surfaces. 462 Public Works Director and City Engineer Mark Culver responded that the numbers stated 463 by Mr. Ramalingam were essentially correct and comparable to his calculations resulting 464 from additional impervious surface with this proposed project and as noted in his 465 summary drainage report. While the basins appear to be shallow, Mr. Culver clarified that 466 they were designed to be shallow as they were constructed with engineered soil that 467 served as a holding cap not just for depth of the depression, and advised that the total 468 actual depth of the engineered soil and the depth of the ponds or depression provided 469 sufficient holding capacity. However, Mr. Culver agreed that they were most likely not 470 going to hold all the water from large rain events, if similar to the intensity of those rains 471 experienced this summer, but opined that from his recollection of his calculations 472 believed that the design of the ponds would hold that water or slow down the runoff so it 473 didn’t leave the project site. Mr. Culver noted that the water would eventually leave the 474 site by infiltrating through soils even though that is not the preferred mitigation. 475 Regarding the positive impact of existing trees on drainage, Mr. Culver opined was 476 difficult to quantify given the variable canopy of trees that also served to prevent water 477 from hitting the ground, even though it dripped off at different spots at different times, 478 along with the root systems absorbing some of that water. With those mature trees gone, 479 Mr. Culver opined that, while it may not look like a net balance will be achieved, and the 480 drainage may not be significantly improved, he considered that it wouldn’t be worse than 481 currently experienced during a normal rain event. 482 Member Murphy asked, if he owned property on any side of this proposed subdivision if 483 implemented, should he expect any more water flowing past his property, or whether the 484 subdivision as proposed would change that flow from any direction. 485 Mr. Culver responded with his previous comments, advising that the developer had 486 attempted to get water into the basins to facilitate the amount of runoff going north. Mr. 487 Culver advised that in part that would depend on the location of downspouts for proposed 488 homes in the subdivision, and how the long-term control was addressed. However, Mr. 489 Culver stated that he wouldn’t anticipate a lot of additional flow to the north, with that 490 water flowing through that channel for outflow purposes. 491 Mr. Culver sought to correct one statement made during public comment, advising that 492 water was not flowing to the catch basin on Marion Street, but approximately halfway 493 between Marion and the Mueller property, of approximately 1/3 to ½ that length and 494 water flowing through there. Mr. Culver suggested that the speaker may be experiencing 495 that water flow across his property and vegetation growth through that natural channel, 496 noting that the property owner may see water drainage for a longer time depending on 497 rate controls put in place. 498 At the request of Member Murphy, Mr. Culver advised that the private street will not have 499 catch basins as it was not intended to have curbs and gutters. At the request of Member 500 Murphy, Mr. Culver further clarified that the water would flow or drain to the west to the 501 end of the hammer head of that private street, and anticipated the remainder would most 502 likely drain onto Acorn Road; and confirmed that the capacity exists today to handle that 503 additional runoff. 504 Member Bull questioned if the basins surrounding the private street were intended to take 505 care of the height of the property and street, but questioned whether impacts would not 506